The Collaborative International Dictionary of English v.0.48:

Ark \Ark\ ([aum]rk), n. [OE. ark, arke, arche, AS. arc, earc,
   earce, fr. L. arca, fr. arcere to inclose, keep off; akin to
   Gr. 'arkei^n to keep off.]
   1. A chest, or coffer. [Obs.]
      [1913 Webster]

            Bearing that precious relic in an ark. --Spenser.
      [1913 Webster]

   2. (Jewish Hist.) The oblong chest of acacia wood, overlaid
      with gold, which supported the mercy seat with its golden
      cherubs, and occupied the most sacred place in the
      sanctuary. In it Moses placed the two tables of stone
      containing the ten commandments. Called also the Ark of
      the Covenant.
      [1913 Webster]

   3. The large, chestlike vessel in which Noah and his family
      were preserved during the Deluge. --Gen. vi. Hence: Any
      place of refuge.
      [1913 Webster]

   4. A large flatboat used on Western American rivers to
      transport produce to market.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Ark
    n 1: (Judaism) sacred chest where the ancient Hebrews kept the
         two tablets containing the Ten Commandments [syn: Ark,
         Ark of the Covenant]
    2: a boat built by Noah to save his family and animals from the
       flood

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "ark":
   Agnus Dei, Holy Grail, Host, Pieta, Sanctus bell, Sangraal,
   asperger, asperges, aspergillum, bambino, beadroll, beads, candle,
   censer, chaplet, ciborium, cross, crucifix, cruet, eucharistial,
   holy cross, holy water, holy-water sprinkler, icon, incensory,
   matzo, menorah, mezuzah, mikvah, monstrance, osculatory,
   ostensorium, paschal candle, pax, phylacteries, prayer shawl,
   prayer wheel, pyx, relics, rood, rosary, sacramental,
   sacred relics, sacring bell, shofar, sukkah, tabernacle, tallith,
   thurible, urceole, veronica, vigil light, votive candle



Easton's 1897 Bible Dictionary:

Ark
   Noah's ark, a building of gopher-wood, and covered with pitch,
   300 cubits long, 50 cubits broad, and 30 cubits high (Gen.
   6:14-16); an oblong floating house of three stories, with a door
   in the side and a window in the roof. It was 100 years in
   building (Gen. 5:32; 7:6). It was intended to preserve certain
   persons and animals from the deluge which God was about to bring
   over the earth. It contained eight persons (Gen. 7:13; 2 Pet.
   2:5), and of all "clean" animals seven pairs, and of "unclean"
   one pair, and of birds seven pairs of each sort (Gen. 7:2, 3).
   It was in the form of an oblong square, with flat bottom and
   sloping roof. Traditions of the Deluge, by which the race of man
   was swept from the earth, and of the ark of Noah have been found
   existing among all nations.

     The ark of bulrushes in which the infant Moses was laid (Ex.
   2:3) is called in the Hebrew _teebah_, a word derived from the
   Egyptian _teb_, meaning "a chest." It was daubed with slime and
   with pitch. The bulrushes of which it was made were the papyrus
   reed.

     The sacred ark is designated by a different Hebrew word,
   _'aron'_, which is the common name for a chest or coffer used
   for any purpose (Gen. 50:26; 2 Kings 12:9, 10). It is
   distinguished from all others by such titles as the "ark of God"
   (1 Sam. 3:3), "ark of the covenant" (Josh. 3:6; Heb. 9:4), "ark
   of the testimony" (Ex. 25:22). It was made of acacia or shittim
   wood, a cubit and a half broad and high and two cubits long, and
   covered all over with the purest gold. Its upper surface or lid,
   the mercy-seat, was surrounded with a rim of gold; and on each
   of the two sides were two gold rings, in which were placed two
   gold-covered poles by which the ark could be carried (Num. 7:9;
   10:21; 4:5,19, 20; 1 Kings 8:3, 6). Over the ark, at the two
   extremities, were two cherubim, with their faces turned toward
   each other (Lev. 16:2; Num. 7:89). Their outspread wings over
   the top of the ark formed the throne of God, while the ark
   itself was his footstool (Ex. 25:10-22; 37:1-9). The ark was
   deposited in the "holy of holies," and was so placed that one
   end of the poles by which it was carried touched the veil which
   separated the two apartments of the tabernacle (1 Kings 8:8).
   The two tables of stone which constituted the "testimony" or
   evidence of God's covenant with the people (Deut. 31:26), the
   "pot of manna" (Ex. 16:33), and "Aaron's rod that budded" (Num.
   17:10), were laid up in the ark (Heb. 9:4). (See TABERNACLE
   ¯T0003559) The ark and the sanctuary were "the beauty of Israel"
   (Lam. 2:1). During the journeys of the Israelites the ark was
   carried by the priests in advance of the host (Num. 4:5, 6;
   10:33-36; Ps. 68:1; 132:8). It was borne by the priests into the
   bed of the Jordan, which separated, opening a pathway for the
   whole of the host to pass over (Josh. 3:15, 16; 4:7, 10, 11, 17,
   18). It was borne in the procession round Jericho (Josh. 6:4, 6,
   8, 11, 12). When carried it was always wrapped in the veil, the
   badgers' skins, and blue cloth, and carefully concealed even
   from the eyes of the Levites who carried it. After the
   settlement of Israel in Palestine the ark remained in the
   tabernacle at Gilgal for a season, and was then removed to
   Shiloh till the time of Eli, between 300 and 400 years (Jer.
   7:12), when it was carried into the field of battle so as to
   secure, as they supposed, victory to the Hebrews, and was taken
   by the Philistines (1 Sam. 4:3-11), who sent it back after
   retaining it seven months (1 Sam. 5:7, 8). It remained then at
   Kirjath-jearim (7:1,2) till the time of David (twenty years),
   who wished to remove it to Jerusalem; but the proper mode of
   removing it having been neglected, Uzzah was smitten with death
   for putting "forth his hand to the ark of God," and in
   consequence of this it was left in the house of Obed-edom in
   Gath-rimmon for three months (2 Sam. 6:1-11), at the end of
   which time David removed it in a grand procession to Jerusalem,
   where it was kept till a place was prepared for it (12-19). It
   was afterwards deposited by Solomon in the temple (1 Kings
   8:6-9). When the Babylonians destroyed Jerusalem and plundered
   the temple, the ark was probably taken away by Nebuchadnezzar
   and destroyed, as no trace of it is afterwards to be found. The
   absence of the ark from the second temple was one of the points
   in which it was inferior to the first temple.